Search

Video game addiction is a term that describes games that dominate a person most of the time. However, the degree of addiction and the amount of time spent playing vary from one type of game to another. So this literature review will explore the mechanism of addiction in terms of different game types, analyzing the relationship between the causes of game addiction in terms of 3 models (dopamine, operant conditioning, and feeling-state theory). In order to figure out what the most attractive type of game is, This is done by classifying all kinds of games into 10 categories and creating a ranking list for all games from 5 different websites. Those websites are chosen randomly from the search engines such as Google and Bing. The results are based on prior studies that looked into the causes of game addiction in each category and analyzed those games by three models. The results suggest that the mechanism of video game addiction varies between games.

A Pd-catalyzed cross-coupling of aryl trifluoroborates with arylsulfonyl chlorides has been successfully achieved. This transformation is a new method for the Suzuki–Miyaura-type reaction of aryl trifluoroborates via the cleavage of C S bond, thus providing an alternative synthesis of biaryls. The reported cross-coupling reactions are tolerant to many common functional groups regardless of electron-donating or electron-withdrawing nature, making these transformations attractive alternatives to the traditional Suzuki–Miyaura coupling approaches. Copyright © 2016 John Wiley & Sons, Ltd.

Li 2 SrSiO 4 :Eu 2+ /Ce 3+ phosphors have been synthesized by solid state reaction. Eu 2+ and/or Ce 3+ doped Li 2 SrSiO 4 have the hexagonal crystal structure, indicating the doped Eu 2+ and/or Ce 3+ ions have no influence on the crystal structure of Li 2 SrSiO 4 . Under the excitation at 365 nm, Eu 2+ or Ce 3+ doped Li 2 SrSiO 4 phosphors give characteristic emission bands of Eu 2+ or Ce 3+ , respectively. For Li 2 SrSiO 4 :Eu 2+ /Ce 3+ phosphors with the fixed Ce 3+ concentration, two emission bands originating from Eu 2+ and Ce 3+ can be observed. On the basis of luminescent properties of Li 2 SrSiO 4 :Eu 2+ /Ce 3+ phosphors, we can conclude that energy transfer from Ce 3+ to Eu 2+ occurs in Li 2 SrSiO 4 .

NaBaPO 4 :Eu 2+ /Tb 3+ phosphors were synthesized by the hydrothermal process. The phase structure of obtained samples was characterized by powder X-ray diffraction. The morphology and size were obtained by field emission scanning electron microscope. Under the excitation at 346 nm, NaBaPO 4 :Eu 2+ /Tb 3+ phosphors exhibited the emission band originating from the 4f 6 5d 1 → 4f 7 transitions of Eu 2+ and the emission bands originating from the 5 D 4 → 7 F j transitions of Tb 3+ . The intensities and lifetimes of Eu 2+ decrease with increasing Tb 3+ concentrations. On the basis of luminescence properties of NaBaPO 4 :Eu 2+ /Tb 3+ phosphors, we can conclude the energy transfer occurs between Eu 2+ and Tb 3+ in NaBaPO 4 host.

Power dispatch problems become more complex when the weight of uncertain renewable resources in the power system gradually increases in recent years. To make use of renewable energy, such as wind energy, more adequately, wisely and intelligently, higher requirements are placed on the level of inter-region power dispatch coordination. In the context, solving the problem of power dispatch on a large scale in near-real-time (5 min in this paper) becomes more important. In this paper, the power dispatch was treated as a sequential decision-making problem and Deep Reinforcement Learning (DRL) with continuous control was introduced to offer a smarter solution. In this way, we designed a novel interactive learning environment based on the economic power dispatch model for the DRL algorithm and we proposed two feasible implementations to handle the different application scenarios. As a result, DRL with a continuous control method has a great performance in our proposed implementations. Moreover, we found that dispatching data richness has a significant influence on the generalization of the learned policy.

The purpose of this paper is to study the following system of nonlinear operator equations for N-variable pseudo-contractive mappings $$T_1, T_2,\ldots ,T_N$$ in a Banach space: $$\begin{aligned} {\left\{ \begin{array}{ll} T_1(x_{1},x_{2},\ldots ,x_{N})=x_1,\\ T_2(x_{1},x_{2},\ldots ,x_{N})=x_2,\\ T_3(x_{1},x_{2},\ldots ,x_{N})=x_3,\\ \ \ \ \ \ \ \ \cdots \\ T_N(x_{1},x_{2},\ldots ,x_{N})=x_N.\\ \end{array}\right. } \end{aligned}$$ The existence theorems of solutions are proved using a comprehensive analytical method. To get the expected results, the reflexivity of the product of Banach space and Opial’s condition of the product of Banach spaces are discussed. Meanwhile, the weak topology of the product of Banach spaces and normal structure of the product of Banach spaces are also discussed. The results of this article improve and extend the previous classical results given in the literature.

We prove some existence theorems for solutions of a certain system of multivariate nonexpansive operator equations and calculate the solutions by using the generalized Mann and Halpern iterative algorithms in uniformly convex and uniformly smooth Banach spaces. The results of this paper improve and extend the previously known ones in the literature.

The effects of aging precipitates on microstructure, mechanical properties and damping capacities of Mg–Zn–Y–Nd alloy were investigated in this study. The structure results indicate that the as-cast alloys consist of α-Mg and W-phase when Zn/RE (rare earth element) weight ratio is about 1.7. After solution-aging treatment, the dissolved W-phase precipitates in the form of large amount of nano-scaled MgZn 2 and Mg 12 Nd phases. The tensile strengths of aged Mg–Zn–Y–Nd alloys are continuously enhanced with the precipitation of MgZn 2 and Mg 12 Nd phase particles, the highest ultimate tensile strength, yield strength and elongation reach up to 257 MPa, 152 MPa and 13.9%. The aging precipitates inhibit deformation twin from growing up and decrease its size, this favors homogeneous deformation and reduces the source of crack initiation, which results in the high elongation of aged Mg–Zn–Y–Nd alloys. The damping capacities of aged Mg–Zn–Y–Nd alloys decrease dramatically at high strain–amplitude stage compared with that of as-cast alloy. The appearance of aging twins and movement or slippage of thin twin boundaries can explain the better damping and unusual damping growth in aged Mg–3.0%–0.9%Y–0.9%Nd (wt%) alloy and Mg–4.0%Zn–1.2%Y–1.2%Nd (wt%) alloys (alloys 2 and 3). The formation of aging twin relates closely to the amount of aging precipitates, no aging twin occurs in the aged Mg–2.0%Zn–0.6%Y–0.6%Nd (wt%) alloy (alloy 1) due to lower precipitates content. The aged Mg–4.0%Zn–1.2%Y–1.2%Nd (wt%) alloy (alloy 3) with more precipitates shows lower damping values than Mg–3.0%Zn–0.9%Y–0.9%Nd (wt%) alloy (alloy 2) because of the stronger pinning effect of precipitates on dislocation.

The effect of long-period stacking ordered (LPSO) structure on mechanical and damping properties of as-cast Mg–Zn–Y–Zr alloy were investigated. Obtained results indicate that the Mg– x %Zn–2 x %Y–0.6%Zr alloys are mainly comprised of α-Mg and LPSO phase. The grain sizes of the Mg–Zn–Y–Zr alloys are obviously refined and the mechanical properties are improved continuously with the formation of LPSO phase, with a maximum value of 222.5 MPa in ultimate tensile strength and 18.9% in elongation. The fracture mechanism of alloys transforms from cleavage fracture to quasi-cleavage fracture with increasing amount of LPSO phase. The damping capacities of Mg–Zn–Y–Zr alloys increase continuously with the increasing LPSO phase and the damping behavior can be explained by the moving model of Shockley partial dislocation. Due to the stacking fault probability, the LPSO phase in the Mg–Zn–Y–Zr alloys could be new damping source to dissipate energy so as to contribute to the improvement of damping capacities.

NaGd(WO4)2:RE3+ (RE = Eu, Tb, Tm) phosphors were synthesized by a hydrothermal process. The XRD and FTIR results show that the hydrothermal time has obvious influence on the crystallization of samples. The longer hydrothermal time benefits to the higher crystallization of NaGd(WO4)2:RE3+ samples. All of the excitation spectra of NaGd(WO4)2:RE3+ samples show the charge transfer bands, which suggests the effective energy transfer between the WO4 2− group and RE3+ ions. Under the excitation of 288 nm, NaGd(WO4)2:RE3+ (RE = Eu, Tb, Tm) phosphors show emissions in red, green, and blue regions, respectively. The results of this work indicate that NaGd(WO4)2:RE3+ (RE = Eu, Tb, Tm) phosphors have potentials to be used as red, green, and blue emitting phosphors.

We synthesized Sr2SiO4:Eu3+ phosphors with spherical morphology by a spray-drying process. The obtained samples were characterized by XRD, SEM, and spectrophotometer. The XRD results show that samples have good crystallinity after the heat-treatment at 1150 °C. The higher temperature has no obvious influence on the crystallinity and will destroy the spherical morphology. The SEM results show that the phosphors are microspheres with size in the range of 0.8–2.1 μm when they were heat treated at 1050 °C and 1150 °C. The excitation and emission spectra of the samples indicate that Eu3+ ions doped into Sr2SiO4 host successfully. The Sr2SiO4:Eu3+ sample heat-treated at 1150 °C has the highest emission intensity and the longest decay times. The results of this work indicate that the optimized heat-treatment temperature should be at 1150 °C for Sr2SiO4:Eu3+ micro-spherical phosphors synthesized by the spray-drying process.

Let K be a nonempty closed convex and bounded subset of a reflexive Banach space X. Let \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$A_{1}, A_{2},\ldots,A_{N}$\end{document}A1,A2,…,AN be N-variables monotone demi-continuous mappings from \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$K^{N}$\end{document}KN into X. Then: (1) the system of multivariate variational inequalities \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\textstyle\begin{cases} \langle A_{1}(x_{1},x_{2},\ldots,x_{N}), y_{1}-x_{1} \rangle\geq0, &\forall y_{1} \in K,\\ \langle A_{2}(x_{1},x_{2},\ldots,x_{N}), y_{2}-x_{2} \rangle\geq0, &\forall y_{2} \in K,\\ \cdots\\ \langle A_{N}(x_{1},x_{2},\ldots,x_{N}), y_{N}-x_{N} \rangle\geq0, &\forall y_{N} \in K,\\ \end{cases} $$\end{document}{〈A1(x1,x2,…,xN),y1−x1〉≥0,∀y1∈K,〈A2(x1,x2,…,xN),y2−x2〉≥0,∀y2∈K,⋯〈AN(x1,x2,…,xN),yN−xN〉≥0,∀yN∈K, has a solution \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$(x_{1}^{*},x_{2}^{*},\ldots,x_{N}^{*}) \in K^{N}$\end{document}(x1∗,x2∗,…,xN∗)∈KN; (2) the set of solutions of this system of multivariate variational inequalities is closed convex in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$K^{N}$\end{document}KN; (3) if \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$A_{1}, A_{2},\ldots,A_{N}$\end{document}A1,A2,…,AN are also strictly monotone, this system of multivariate variational inequalities has a unique solution.

The effects of solution treatment and aging on microstructure, mechanical properties and damping capacity of as-cast Mg–3%Zn–0.9%Y–0.6%Nd–0.6%Zr (wt%) (ZW30N) magnesium alloy were investigated. The as-cast alloy is comprised of α-Mg matrix and W-phase. After solution treatment at 540 °C for 8 h, the net-like interdendritic W-phase dissolves into the matrix and small Zr-containing particles precipitate at grain interiors. Due to the precipitation of fine W, β1′ and β2′ phases during the subsequent aging treatment, the ultimate tensile strength, yield strength and elongation of the alloy significantly improved from 180 MPa, 119 MPa and 12.3% in as-cast alloy to 262 MPa, 161 MPa and 15.2%, respectively. The damping capacity of heat-treated Mg–Zn–Y–Nd–Zr alloys decreases dramatically with respect to that of as-cast condition. In the solution-treated alloy, increasing number of Zr-containing particles and solute atoms in the matrix is responsible for the damping decline. For the peaked-aged alloy, the favorable damping and unusual damping growth at high strain amplitude stage are believed to be closely related to the formation of a twin dislocation, which produces new energy-dissipation source besides dislocation damping.

Sr3Al2O6:Ce3+ powders were synthesized using a solid state reaction method in air with addition of H3BO3. The effects of Ce3+ dopant concentrations and the weight ratio (wt) of H3BO3 to total raw materials weight on the formation of Sr3Al2O6:Ce3+ samples were investigated. Single-phase and well-crystallized Sr3Al2O6:Ce3+ samples can be obtained when the addition of H3BO3 is lower than 7 wt%. The excitation spectrum indicates that Sr3Al2O6:Ce3+ phosphor powders exhibit two excitation bands centered at 345 and 462 nm. The emission spectrum shows that Sr3Al2O6:Ce3+ phosphor powders exhibit an emission band peaked at 536 nm when excited at 462 nm. Sr3Al2O6:Ce3+ sample at the Ce3+ concentration of 5 mol% shows the strongest emission intensity. The addition of H3BO3 has obvious influence on phase and emission intensity of Sr3Al2O6:Ce3+ phosphors. The results show that the Sr2.95Ce0.05Al2O6 sample with the 7 wt% addition of H3BO3 has the highest emission intensity and the longest lifetime.

This paper presents a boundary control formulation for distributed parameter systems described by partial differential equations (PDEs) and whose output is given by a spatial integral of weighted functions of the state. This formulation is directly applicable to the control of small robotic aircraft with articulated flexible wings, where the output of interest is the net aerodynamic force or moment. The deformation of flexible wings can be controlled by actuators that are located at the root or the tip of the wing. The problem of designing a tracking controller for wing twist is addressed using a combination of PDE backstepping for feedback stabilization and feed-forward trajectory planning. We also design an adaptive tracking controller for wing tip actuators. For wing bending, we present a novel control scheme that is based on a two-stage perturbation observer. A trajectory planning-based feed-forward tracker is designed using only one component of the observer whose dynamics are homogeneous and amenable to trajectory planning. The two components, put together, estimate the external forces and unmodeled system dynamics. The effectiveness of the proposed controllers for twist and bending is demonstrated by simulations. This paper also reports experimental validation of the perturbation-observer-based controller for beam bending.

The purpose of this paper is to present a new class of probabilistic normed spaces and to study fixed point problems in this class of probabilistic normed spaces. This paper includes the following two contents: (1) The definition of a new class of probabilistic normed spaces, the so-called S-probabilistic normed spaces, is given. In order to study the fixed point problems, some relevant properties of S-probabilistic normed spaces are discussed and some basic useful results are obtained; (2) The notion of probabilistic weak convergence is firstly presented in this paper. Therefore the probabilistic weak and strong convergence theorems of fixed points for nonexpansive mappings, asymptotically nonexpansive mappings and strongly pseudocontractive mappings are also proved by using the new methods and techniques.

A novel perturbation observer-based PDE boundary control law for beam bending is derived based on a combination of perturbation observers and polynomial trajectory planning. The perturbation observer consists of two components. The first stage employs the “particular” solution of the original dynamics with disturbances while its boundary conditions are set to zero. In contrast, the dynamics of the “homogeneous component” are independent of the beam dynamics, but its boundary conditions are identical to those of the beam. A tracking boundary control law, based on trajectory planning, is designed for the homogeneous component, and the same control signal is also applied to the beam. The stability of the adaptive perturbation-observer is proven by Lyapunov stability in the spatial L2 sense, while stability conditions are derived for a finite dimensional ODE analogue of the infinite dimensional closed loop PDE system. This paper also reports on one of the first experimental demonstrations of a controller designed entirely using a PDE boundary control formulation.

The purpose of this paper is to present the definition of $$(\phi ,\varphi )$$ -contractive mapping and to discuss the relation of $$\psi$$ -contractive mappings and $$(\phi ,\varphi )$$ -contractive mappings. Furthermore, the generalized $$(\phi ,\varphi )$$ -contraction mapping principle has been proved without the uniqueness condition. Meanwhile, the generalized $$\psi$$ -contraction mapping principle has been obtained by using an ingenious method.

The purpose of this article is to establish a kind of non-convex hybrid iteration algorithms and to prove relevant strong convergence theorems of common fixed points for a uniformly closed asymptotically family of countable quasi-Lipschitz mappings in Hilbert spaces. Meanwhile, the main result is applied to get the common fixed points of finite family of quasi-asymptotically nonexpansive mappings. It is worth pointing out that a non-convex hybrid iteration algorithm is first presented in this article, a new technique is applied in our process of proof. Finally, an example is given which is a uniformly closed asymptotically family of countable quasi-Lipschitz mappings. The results presented in this article are interesting extensions of some current results.